JP6460372B2 - Magnetic sensor, method for manufacturing the same, and measuring instrument using the same - Google Patents

Description

  The present invention relates to a magnetic sensor, and more particularly to a magnetic sensor using a magnetoresistive effect element.

  As a measuring device, a magnetic sensor capable of detecting a change in a magnetic field has been developed, and is used for various applications such as an ammeter and a magnetic encoder. An example of such a magnetic sensor is disclosed in Non-Patent Document 1 below, which uses a GMR element (Giant Magneto Resistive Effect Element) as an element for detecting a change in a magnetic field. The element is an element in which a resistance value output according to the input magnetism changes, and based on the output resistance value, a change in the detected magnetic field can be measured.

  And as an example of the concrete structure of the magnetic sensor using a GMR element, as shown in patent document 1, four GMR elements are arrange | positioned on a board | substrate and a bridge circuit is comprised. Then, by detecting the differential voltage of the bridge circuit, a change in the resistance value of the GMR element due to a change in the magnetic field to be detected is detected. As a result, a sensor that is highly sensitive to changes in the magnetic field can be configured.

  Specifically, the magnetic sensor disclosed in Patent Document 1 is a spin valve type GMR element (giant to change in output resistance value according to the direction of an input magnetic field, as an element for detecting a change in a magnetic field. A GMR chip (magnetic field detection chip) using a magnetoresistive element is provided. The GMR elements are fixedly magnetized in a predetermined direction on one surface so that a magnetic field in a predetermined direction can be detected. At this time, in order to reduce the size of the GMR chip and reduce variations in individual resistance values, four GMR elements forming a bridge circuit are formed on one GMR chip. For this reason, the magnetization fixed directions of all four GMR elements are all the same direction.

  When a unidirectional magnetic field is detected using a GMR chip that forms such a bridge circuit, in Patent Document 1, a pair of magnetoresistive elements that are not connected to each other in the bridge circuit are substantially the same. A magnetic body that changes the direction of the magnetic field input to the magnetoresistive effect element is disposed around the element forming portion formed at the location.

  Further, the magnetic body can change an external magnetic field in one direction in different directions between magnetoresistive elements. Thus, the two element forming portions within the bridge circuit are arranged so that the magnetic field is incident on the one in the magnetization fixed direction and the other in the opposite direction. As a result, a large differential voltage is output from the bridge circuit to improve the detection accuracy of the magnetic field in one direction.

JP2009-276159

NVE CORPORATION (USA), “NVE CORPORATION GMR Sensor Catalog”, [online], P7, [March 14, 2014 search], Internet <URL: http: // www. nve. com / Downloads / catalog. pdf>

  However, in the technique disclosed in Patent Document 1, a step of forming the bridge circuit configured by the element forming unit and a step of arranging a magnetic body that changes the direction of a magnetic field input to the magnetoresistive element. However, there is a problem that the manufacturing cost increases due to an increase in the number of strokes.

  Furthermore, since the step of arranging the magnetic body is a step separate from the step of forming the bridge circuit, it is difficult to place the magnetic body with high accuracy, and due to variations in the position where the magnetic body is arranged. There is also a problem that the magnetic field detection accuracy decreases.

  In addition, since the step of arranging the magnetic body is a step different from the step of forming the bridge circuit, an adhesion step for fixing the magnetic body is also required, and there is a problem that the manufacturing cost increases.

  In the manufacturing method using the bonding step for fixing the magnetic body, the bonding step or bonding is performed in a direction (Z-axis direction) perpendicular to the surface on which the magnetic body and the magnetoresistive element are formed. There is a problem that a gap (gap) is formed by the agent, and the distance between the magnetic body and the magnetoresistive element in the Z-axis direction is widened, and the magnetic field detection accuracy is lowered.

  Furthermore, in addition to the jig or apparatus for placing the magnetic body, a jig or apparatus in the bonding process for fixing the magnetic body is required, which increases the manufacturing cost.

  In addition, the magnetic body must be produced in a process separate from the magnetoresistive element forming process, and the shape and size are limited. Therefore, there is a problem that the sensor cannot be reduced in size. there were.

  The minimum dimension (surface resolution) that can be detected by the sensor in a direction parallel to the surface on which the magnetoresistive element is formed is limited by the dimension of the magnetic material in the magnetization fixed direction. Therefore, the magnetic body must be produced in a process separate from the process of forming the magnetoresistive effect element, and the reduction in the size of the magnetic body is limited, thereby improving the surface resolution. There was no problem.

  Therefore, an object of the present invention is to provide a magnetic sensor that can improve the detection accuracy of a magnetic field while achieving downsizing and cost reduction, which are the problems described above.

  Therefore, a magnetic sensor according to one aspect of the present invention is connected to a plurality of magnetoresistive effect elements whose resistance values change depending on the direction of an input magnetic field, and detects a differential voltage between predetermined connection points. It has a bridge circuit configured as possible. Further, a magnetic body that changes the direction of the magnetic field input to the magnetoresistive effect element is disposed around the bridge circuit, and the magnetic body is formed by a film forming process.

  The magnetoresistive element and the magnetic body are preferably arranged on the same straight line (X-axis direction) along the magnetization fixed direction of the magnetoresistive element.

  More specifically, the magnetic sensor includes a pair in which the bridge circuit includes the four magnetoresistive elements and is connected to each other on the opposite side of the differential output unit in the bridge circuit. A first magnetic circuit in which first and second element forming portions formed by the two magnetoresistive effect elements are formed side by side in the X-axis direction, and the magnetic body is disposed between the element forming portions. A second magnetic circuit forming portion having a forming portion and having the magnetic body disposed between third and fourth element forming portions formed in the same configuration as the first magnetic circuit forming portion. And the second magnetic circuit forming unit is disposed apart from the first magnetic circuit forming unit in a direction perpendicular to the magnetization fixed direction (Y-axis direction). The magnetoresistive element of the forming part and the second magnetic circuit forming part is the differential output part It may be connected, respectively.

  The magnetoresistive effect element may be arranged so that the magnetization fixed directions of the magnetoresistive effect element are all directed in the same direction.

  Further, in the magnetic body, a dimension in a direction perpendicular to the surface on which the magnetoresistive effect element is formed is h (height of the magnetic substance), and a dimension in the magnetosensitive direction of the magnetoresistive effect element is w ( The ratio of the dimensions h / w is preferably 1 or more.

  It is desirable that the magnetoresistive effect element is disposed on the inner side of the magnetic body forming region in a direction perpendicular to the magnetic sensing direction of the magnetoresistive effect element.

  The magnetic body is desirably disposed on the surface on which the magnetoresistive element is formed.

  And the said magnetic body may be arrange | positioned through the laminated structure containing one or more insulating films from the surface in which the said magnetoresistive effect element is formed.

  Moreover, the said magnetic body is good in it being a soft magnetic body, for example.

  The first magnetic body and the second magnetic body disposed in the first magnetic circuit forming section and the second magnetic circuit forming section may be the same body.

  Moreover, the measuring device which is the other form of this invention is comprised including the magnetic sensor mentioned above.

  According to the above invention, since the magnetic body is formed by a film forming process, the shape of the magnetic body can be freely formed, so that the magnetic field detection accuracy can be further improved.

  At this time, in particular, since the element forming portion and the magnetic body are formed by the same manufacturing process, the magnetic body can be arranged with high accuracy with respect to the position of the element forming portion. In addition, manufacturing variations can be suppressed. Furthermore, an increase in manufacturing cost depending on the shape of the magnetic body can be suppressed, and the cost of the sensor can be reduced.

  Furthermore, since the magnetic body is formed by a film forming process, not only the magnetic sensor can be formed on one chip, but also the magnetic sensor can be reduced in height and size, Thereby, the manufacturing efficiency of the chip can be improved, and the cost of the sensor can be reduced.

  The minimum dimension (surface resolution) that can be detected by the sensor in a direction parallel to the surface on which the magnetoresistive element is formed is limited by the dimension of the magnetic material in the magnetization fixed direction. From the above, by forming the magnetic body by a film forming process, the magnetic body is formed in a small size while the magnetic body is formed in a small size, and further, the magnetic body is arranged with high accuracy, The surface resolution can be improved in the magnetic field detection of the sensor.

  Since the present invention is configured and functions as described above, according to this, since the magnetic body is formed by a film forming process, the magnetic body is disposed at a place where the magnetoresistive effect element is disposed. Since it can arrange | position with high precision, while improving a magnetic field detection precision, manufacturing variation can also be suppressed.

  The minimum dimension (surface resolution) that can be detected by the magnetic sensor in the direction parallel to the surface on which the magnetoresistive element is formed is limited by the dimension of the magnetization fixing direction of the magnetic body. Therefore, the surface resolution in the magnetic field detection of the sensor can be improved by forming the magnetic body by a film forming process and arranging the magnetic body with high accuracy while keeping the magnetic body small. You can also.

  In addition, the magnetoresistive effect element is disposed inside the magnetic body forming region in a direction perpendicular to the magnetosensitive effect direction of the magnetoresistive effect element. On the other hand, the magnetic field from the magnetic body can be uniformly incident, and the detection accuracy of the magnetic sensor can be improved.

  Further, in the magnetic body, the dimension in the direction perpendicular to the surface on which the magnetoresistive effect element is formed is h (height of the magnetic body), and the dimension in the magnetosensitive direction of the magnetoresistive effect element is w ( Since the ratio h / w of the dimensions is 1 or more, the magnetic field can be efficiently incident on the magnetosensitive direction of the magnetoresistive element. The detection accuracy of the magnetic sensor can be improved.

  Further, since the magnetic body is formed by a film forming process, the shape of the magnetic body can be freely formed, and an increase in manufacturing cost depending on the shape of the magnetic body can be suppressed. . For example, even if the magnetic body has a complicated shape such as a chamfered portion or a notch at a corner, the number of manufacturing steps is not increased.

  Since the first step of forming the bridge circuit and the second step of disposing the magnetic body between the element forming portions are performed within the same manufacturing process, the magnetic body can be made with high accuracy. Therefore, it is possible not only to improve the magnetic field detection accuracy but also to suppress manufacturing variation, and to suppress an increase in manufacturing cost.

  Furthermore, since the magnetic body is formed by a film forming process, not only the magnetic sensor can be formed on one chip, but also the magnetic sensor can be reduced in height and size, Thereby, the manufacturing efficiency of the chip can be improved, and the cost of the sensor can be reduced.

It is a figure explaining the characteristic of a GMR element. It is a figure which shows the structure 1 of a GMR chip | tip. It is a one part enlarged view of a GMR chip. It is a figure which shows the bridge circuit comprised by the GMR element formed in the GMR chip | tip. 1 is a diagram illustrating a configuration of a magnetic sensor in Embodiment 1. FIG. It is a figure which shows the mode of the magnetic field with respect to the magnetic sensor in Embodiment 1. FIG. It is a figure which shows the structure 2 and Embodiment 2 of a GMR chip | tip. It is a figure which shows the structure 3 of a GMR chip | tip. It is a figure which shows the structure of the ammeter in Embodiment 3. FIG. It is a figure which shows the structure of the ammeter in Embodiment 3. FIG. It is a figure which shows the structure of the encoder in Embodiment 4. It is a figure which shows the structure of the encoder in Embodiment 4.

  A specific configuration of the present invention will be described in the embodiment. Hereinafter, in Embodiments 1 and 2, the configuration of the magnetic sensor according to the present invention will be described, and in Embodiments 3 to 4, various measuring devices using the magnetic sensor will be described.

A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram for explaining the characteristics of the GMR element. 2 to 4 are diagrams showing an example of the GMR chip. 5 to 6 are diagrams showing an example of the magnetic sensor in the present embodiment.
First, characteristics of the GMR element used in the present invention will be described with reference to FIG. The GMR element is a spin valve type GMR element (giant magnetoresistive effect element) in which the output resistance value changes according to the direction of the input magnetic field. FIG. 1 shows the relationship between the penetration angle of the magnetic field H with respect to the GMR element and the resistance value.

  The GMR chip 100 in the example of FIG. 1A has a GMR element formed on the upper surface thereof. This GMR element is configured to be fixed in the direction of arrow A so that a magnetic field in the direction of arrow A can be detected.

  In FIG. 1A, the GMR element is disposed in a magnetic field H incident perpendicularly to the formation surface of the GMR element. In this case, the resistance value of the GMR element is “Ro” as shown in FIG. On the other hand, when the direction of the magnetic field H is inclined, as shown by the dotted line in FIG. 1A, the incident angle of the magnetic field H with respect to the GMR element surface is −Δθ (Δ (delta): change amount from the vertical direction. Or tilted by an angle of + Δθ. Then, since the GMR element is magnetized and fixed in one direction as described above, the direction of the magnetic field changes in that direction, and the MR resistance value changes as shown in FIG. Thus, when the resistance value is set to Ro in a state where the direction of the incident magnetic field is vertical, the resistance value of the GMR element greatly changes particularly when the direction of the magnetic field H is inclined by a minute angle. Has characteristics.

[Constitution]
Next, the configuration of the GMR chip 10 used in the magnetic sensor 1 of this embodiment will be described with reference to FIGS. As shown in FIG. 2, the GMR chip 10 has a substantially rectangular parallelepiped shape, and four GMR elements R1, R2, R3, and R4 are formed on one surface (upper surface) thereof. These GMR elements R1, R2, R3, and R4 are connected as shown in FIG. 4 to form a bridge circuit. That is, the GMR elements R1 and R3 and the GMR elements R2 and R4 are respectively connected in series, and the serially connected GMR elements R1, R3 and R2, R4 are connected in parallel to the power source and closed. The circuit is configured. As a result, it is possible to detect a differential voltage between the connection point Va between the GMR elements R1 and R3 and the connection point Vb between the GMR elements R2 and R4. The bridge circuit is formed in advance on the GMR chip 10 so that the differential voltage can be detected as described above.

  In the present embodiment, particularly, as shown in FIG. 3, of the four GMR elements, two GMR elements R1 and R2 forming a pair connected to each other in the bridge circuit shown in FIG. Are formed side by side on the first element forming portion 11a and the second element forming portion 12a on the direction parallel to the magnetization fixed direction of the magnetoresistive effect element (X-axis direction). In addition, the first magnetic body 21a is formed between the GMR elements R1 and R2 (first and second element forming portions) so as to form the first magnetic circuit on the X-axis direction substantially the same as the GMR elements R1 and R2. The unit 31 is disposed. Further, the other two GMR elements R3 and R4 which form a pair connected to each other in the bridge circuit are connected to the third element forming portion 11b and the fourth element forming portion 12b in the same X-axis direction. It is formed side by side. In addition, the second magnetic body 21b is formed between the GMR elements R3 and R4 (third and fourth element forming portions) and is substantially the same as the second magnetic circuit in the X-axis direction as the GMR elements R3 and R4. The unit 32 is disposed. The GMR elements R1, R2, R3, and R4 are magnetization fixed in the direction of arrow A in FIG. The arrangement positions of the element forming portions 11 and 12 and the magnetic bodies 21a and 21b are arranged on the surface on which the GMR elements R1, R2, R3, and R4 are formed. The arrangement positions of the magnetic bodies 21a and 21b are not limited to the above positions. For example, the GMR elements R1, R2, R3, and R4 may be disposed on a surface on which the GMR elements R1, R2, R3, and R4 are formed via a laminated structure including one or more insulating films.

  As described above, the first magnetic circuit forming unit 31 formed by two GMR elements (R1 and R2) and one magnetic body (21a), two GMR elements (R3, R4), and one The second magnetic circuit forming portions 32 formed of the magnetic body (21b) are formed apart from each other in the direction perpendicular to the magnetization fixed direction of the magnetoresistive effect element. For example, as shown in FIG. 3, magnetic circuit forming portions 31 and 32 are formed in the long side direction of the GMR chip 10, that is, in the vicinity of both ends in the Y-axis direction of FIG.

  In addition, the magnetoresistive effect elements constituting the first magnetic circuit forming portion and the second magnetic circuit forming portion are inward of the magnetic body forming region in the direction perpendicular to the magnetosensitive direction of the magnetoresistive effect element. It is desirable that they are arranged. With this configuration, the magnetic field H in the X-axis direction incident on the GMR elements R1, R2, R3, and R4 from the magnetic material can be made uniform in the element forming portions of the GMR elements R1, R2, R3, and R4. .

  Further, as shown in FIG. 6, in the magnetic body, the dimension in the direction perpendicular to the surface on which the magnetoresistive effect element is formed is h (height of the magnetic body), and the sensitivity of the magnetoresistive effect element is set. When the dimension in the magnetic direction is w (the width of the magnetic material), the ratio h / w of the dimensions is preferably 1 or more, and the larger the value, the better.

  In the magnetic sensor 1 according to the present invention, a magnetic body 21 that changes the direction of the magnetic field H input to the GMR elements R1, R2, R3, and R4 is disposed around the bridge circuit formed on the GMR chip 10 described above. ing. Specifically, as shown in FIG. 5, the magnetic sensor 1 according to the present embodiment has the above-described GMR chip 10 mounted on the substrate B, and each element forming portion of the bridge circuit formed on the GMR chip 10. The first magnetic circuit forming part 31 in which the first magnetic body 21a is formed between 11a and 11b, and the second magnetic circuit forming part 32 in which the second magnetic body 22b is formed between 12a and 12b. It is placed. The magnetic bodies 21 a and 21 b are soft magnetic bodies such as permalloy (Ni—Fe alloy) and sendust (Fe—Si—Al alloy), for example, but the direction of the magnetic field H is a function of the magnetic body 21. The material is not limited as long as it can be changed. Thus, in the present embodiment, in particular, the first magnetic circuit 31 and the second magnetic circuit 32 are in a state of being arranged on the substantially same Y axis.

[Operation]
Next, the operation of the magnetic sensor 1 having the above configuration will be described with reference to FIG. FIG. 6 shows a case where the magnetic sensor 1 is arranged in a magnetic field H substantially perpendicular to the element surfaces of the GMR elements R1, R2, R3, and R4, as in the example of FIG. 4 described above. Then, in this embodiment, as shown in this figure, the magnetic field H is attracted to the magnetic body 21 from above the magnetic body 21 to the vicinity of the center of the magnetic body 21, and The magnetic field H is bent in a direction away from the magnetic body 21 below the center where the element forming portions 11 and 12 are formed. Then, the magnetic field H in the opposite direction is incident on each of the element forming portions 11 and 12 (GMR elements (R1 and R2, R3 and R4)) positioned with the magnetic material 21 in between. Specifically, as indicated by dotted arrows Y1 and Y2 in FIG. 6, a magnetic field H changed in the same direction as the magnetization fixed direction A is incident on the GMR elements R1 and R4 of the element forming portion 11. The magnetic field H changed in the direction opposite to the magnetization fixed direction A is incident on the GMR elements R2 and R3 of the element forming unit 12.

  Then, in the bridge circuit, the resistance values of the GMR elements R1 and R4 and the resistance values of the GMR elements R2 and R3 change to opposite signs. For example, the resistance values of the GMR elements R1, R4 change by + ΔR, and the resistance values of the GMR elements R2, R3 change by -ΔR. As a result, the difference between Va and Vb, which are detection points of the differential voltage, is increased, and a large differential voltage value can be detected. Note that the circuit for detecting the differential voltage is formed on the substrate B, for example, and can be detected by being connected to the bridge circuit formed on the GMR chip 10.

  As described above, the magnetic field detection accuracy can be improved by using the magnetic sensor having the above-described configuration. As a result, the magnetic sensor can be used for various measuring devices. In particular, in this embodiment, the bridge circuit can be formed on one chip, and the magnetic body is formed by a film forming process. Further, since the magnetic material is manufactured by the same manufacturing process as that for forming the GMR element, the variation of individual GMR elements can be reduced. Therefore, the offset voltage in the bridge circuit is suppressed, and the magnetic material is further reduced. Since the body can be arranged with high accuracy with respect to the position of the GMR element, it is possible to further improve the magnetic field detection accuracy. In addition, the GMR element constituting the magnetic body and the bridge circuit can be formed on one chip, so that the entire chip can be reduced in size, thereby improving the manufacturing efficiency of the chip and reducing the sensor. Cost can also be reduced.

[Production method]
Next, a method for manufacturing the magnetic sensor 1 described above will be described. First, a bridge circuit is configured as described above, and four GMR elements R1, R2, R3, and R4 are formed on the GMR chip 10 so as to be disposed in the element forming portions 11 and 12 (first step). . Subsequently, a magnetic body 21 is formed between the element forming portions 11 and 12 on the surface on which the GMR element is formed (second step). The first step and the second step are performed in the same process. Further, if necessary, the GMR chip 10 is arranged on the substrate and various wirings are connected at an arbitrary timing.

  In this manner, the magnetic sensor 1 can be manufactured, and can be used as various measuring devices by being incorporated alone or in another configuration.

Next, a second embodiment of the present invention will be described with reference to FIGS.
[Constitution]
As shown in FIG. 7, the magnetic sensor 1 according to the present embodiment includes the first magnetic body 21 a that is one of the components of the first magnetic circuit unit according to the first embodiment described above and the second sensor. Since the second magnetic body 21b, which is one of the components in the magnetic circuit section, is the same body, in the vicinity of the ends in the Y-axis direction of the GMR elements R1, R2, R3, and R4, The magnetic field H incident on the GMR elements R1, R2, R3, R4 after the direction is changed by the magnetic body 21 can be uniformly incident in the X-axis direction in the X-axis direction, It is possible to suppress variations in the incident direction of the magnetic field H on the GMR elements R1, R2, R3, and R4. Further, since the first magnetic body 21a and the second magnetic body 21b are the same body, the variation in shape caused by the manufacturing in the film forming process accompanying the downsizing of the magnetic body size is suppressed. Is also possible.

  Furthermore, as shown in FIG. 8, the magnetic body 21 may have one or more notches. By having a part of the notches in the magnetic body 21 as described above, it is possible to add an effect such as easy positioning when the GMR chip is arranged in the sensor manufacturing process. The number of the notches is not necessarily limited to two, but may be one or three or more. Here, the “notch” is not particularly limited in shape, and is not limited to a rectangle as shown in FIG. 8, but a square, a shape with a partial arc, or a triangular shape, and the described shape. The shape which combined two or more may be sufficient.

  As described above, the magnetic field detection accuracy can be improved by using the magnetic sensor having the above-described configuration. As a result, the magnetic sensor can be used for various measuring devices. In particular, in this embodiment, the bridge circuit can be formed on one chip, and the magnetic body is formed by a film forming process. Furthermore, since the magnetic material is manufactured by the same manufacturing process as the step of forming the GMR element, variation in individual GMR elements can be reduced, thereby suppressing the offset voltage in the bridge circuit, and further Since the magnetic body can be arranged with high accuracy with respect to the position of the GMR element, the magnetic field detection accuracy can be further improved. In addition, the GMR element constituting the magnetic body and the bridge circuit is formed on one chip, so that the entire chip can be reduced in size, thereby improving the manufacturing efficiency of the chip, Cost reduction can also be achieved.

  Next, a third embodiment of the present invention will be described with reference to FIGS. In the present embodiment, an ammeter will be described as an example of a measuring device using the magnetic sensor 1 described above.

  As shown in FIG. 9, the ammeter includes a substantially square-shaped (annular) magnetic core 5 in which a gap 50 (gap) cut in part is formed. The magnetic sensor 1 described in the first embodiment is arranged. At this time, the magnetic sensor 1 has GMR elements R 1, R 2, R 3, R 4 formed on one of the cut surfaces of the magnetic core 5 that forms the gap 50, that is, one of the mutually opposing wall surfaces that form the gap 50. It is arranged to face each other. And as shown in FIG. 10, the conducting wire 51 (conductor) is arrange | positioned so that the substantial center of the substantially square-shaped magnetic body core 5 may be penetrated, and the electric current which flows into this conducting wire 51 is measured.

  With the configuration described above, when the current I flows through the conducting wire 51, a magnetic field H is generated in a ring shape along the magnetic core 5 surrounding the current I. Then, the magnetic field H is perpendicularly incident on the formation surface of the GMR elements R1, R2, R3, R4 formed in the magnetic sensor 1 disposed in the gap 50. That is, the conducting wire 51 and the magnetic core 5 function as magnetic field generating means for generating a magnetic field measured by the magnetic sensor 1.

  The magnetic field H generated in the magnetic core 5 due to the current I flowing through the conducting wire 51 is bent by the influence of the magnetic body 21 and the like equipped in the magnetic sensor 1 as described in the above embodiments. . As a result, the magnetic field enters the GMR elements R1, R2, R3, and R4 of the magnetic sensor 1 at a predetermined angle. Specifically, the magnetic field H is incident on the element forming portions 11 and 12 (GMR elements (R1 and R2, R3 and R4)) with angles in opposite directions. Then, in the bridge circuit, the resistance values of the GMR elements R1 and R4 and the resistance values of the GMR elements R2 and R3 change to opposite signs. For example, the resistance values of the GMR elements R1, R4 change by + ΔR, and the resistance values of the GMR elements R2, R3 change by -ΔR. As a result, the difference between Va and Vb, which are detection points of the differential voltage, is increased, and a large differential voltage value can be detected.

  As described above, by using the magnetic sensor 1 having the above configuration, the current flowing through the conductive wire 51 can be detected with high accuracy. In particular, in this embodiment, the bridge circuit can be formed on one chip, and the magnetic body is formed by a film forming process. Further, since the manufacturing process is the same as that for forming the GMR element, variation in individual resistance values can be reduced. For this reason, the offset voltage can be suppressed, and the magnetic material can be arranged with high accuracy with respect to the position of the GMR element, so that the magnetic field detection accuracy can be further improved. In addition, since the GMR element constituting the magnetic body and the bridge circuit is formed on one chip, the entire chip can be reduced in size. Then, it can be arranged in the minute gap 50 of the magnetic core 5 as described above, and can be applied to various measuring instruments.

  Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, an encoder (angle sensor) will be described as an example of a measuring device using the magnetic sensor 1 described above.

  As shown in FIG. 11, the encoder includes a magnet 6 (magnetic field generating means) formed in a substantially cylindrical shape by combining a semi-cylindrical N pole and S pole. And this magnet 6 is installed in the board | substrate or the base so that it can rotate on the central axis C of a cylinder, and is equipped with the magnetic sensor 1 mentioned above around the rotation.

  In particular, in this embodiment, two magnetic sensors 1 are arranged so that the radial direction of the magnet 6 and the magnetization fixed directions of the GMR elements R1, R2, R3, and R4 coincide. At this time, the two magnetic sensors 1 are arranged at an angle of 90 degrees with respect to the central axis of the magnet 6.

  As a result, when the magnet 6 rotates, the direction of the magnetic field H from the magnet 6 changes according to the rotation angle, so that each magnetic sensor 1 measures a sinusoidal differential voltage value. For example, a positive voltage with a larger value is obtained as the N pole approaches the magnetic sensor 1, and when the middle of the N pole and the S pole is directed toward the magnetic sensor 1, the voltage becomes 0 voltage, and a smaller value as the S pole approaches. Negative voltage is obtained. Then, since the two magnetic sensors 1 are arranged 90 degrees apart from each other, the voltage values measured in each of them are 90 degrees out of phase.

  The encoder includes a measuring unit 7 connected to the two magnetic sensors 1 to which a differential voltage measured by each magnetic sensor 1 is input. The measurement unit 7 can obtain the rotation angle of the magnet 6 by calculating tan using sin and cos from the voltage values of sinusoidal waveforms with different phases measured by the magnetic sensors 1. Even when the magnet 6 is stationary, the rotation angle of the magnet 6 can be calculated by calculating tan from the outputs of the two magnetic sensors 1 in the same manner, and can also function as an absolute encoder.

  In addition, the structure when using the magnetic sensor 1 for an encoder is not limited to the structure mentioned above. For example, the magnet 6 does not necessarily have to be configured such that the N pole and the S pole are separated for each semi-cylinder, and only half of the outer peripheral surface of the magnet 6 is formed in the N pole, Only a part may be formed in the N pole. Further, the number of magnetic sensors 1 is not necessarily limited to two, and may be one or three or more.

  In the above description, an ammeter and an encoder have been described as an example of a measuring device using the magnetic sensor 1. However, the magnetic sensor 1 according to the present invention is applicable to various other measuring devices.

  The present invention can be used for various measuring devices such as a magnetic sensor, an ammeter, an encoder, and has industrial applicability.

DESCRIPTION OF SYMBOLS 1 Magnetic sensor 10 GMR chip | tip 11,12 Element formation part 21 Magnetic body 31,32 Magnetic circuit formation part 41 Notch part 5 Magnetic body core 50 Gap 51 Conductor 6 Magnet 7 Measurement part R1, R2, R3, R4 GMR element A Magnetization Fixed direction H Magnetic field B Substrate h Magnetic body height w Magnetic body width I Current flowing in the conductor C Cylinder center axis

Claims (8)

A plurality of magnetoresistive effect elements are connected, and a bridge circuit configured to detect a differential voltage between predetermined connection points is provided, and a magnetic field input to the magnetoresistive effect element is provided around the bridge circuit. A magnetic body for changing a direction is disposed, the magnetic body is formed by a film forming process, and the bridge circuit includes four magnetoresistive elements, and the bridge circuit includes a differential output unit. The first and second element forming portions formed of two pairs of magnetoresistive elements that are connected to each other on the opposite side of the magnetoresistive element are magnetized in parallel with the X-axis direction of the magnetoresistive element. The first magnetic circuit forming portion is formed side by side in a fixed direction, and the magnetic body is disposed between the first and second element forming portions, and further, as in the first magnetic circuit forming portion. Pair 2 connected to A second magnetic circuit forming part in which the magnetic body is disposed between third and fourth element forming parts formed side by side in the magnetization fixed direction of the magnetoresistive effect element, and The magnetic circuit forming portion is disposed away from the first magnetic circuit forming portion in the Y-axis direction which is a direction perpendicular to the magnetization fixed direction, and the first magnetic circuit forming portion and the second magnetic circuit forming portion are arranged. The magnetoresistive effect elements of the magnetic circuit forming portion are connected to each other at the differential output portion, and the magnetic body is formed by the same manufacturing process as the step of forming the bridge circuit. the magnetic body and the magnetic circuit forming unit disposed in the second magnetic circuit forming portion is a homologue, and notches have a, the notch is in the Y-axis direction of the magnetic magnetic characterized that you have been formed in the center of the end portion Capacitors. The magnetic sensor according to claim 1, wherein the magnetoresistive element and the magnetic body are arranged on the same straight line along a magnetization fixed direction of the magnetoresistive element. The magnetic sensor according to claim 1, wherein the magnetoresistive effect elements are arranged such that the magnetization fixed directions of the magnetoresistive effect elements are all in the same direction. When the dimension in the direction perpendicular to the surface on which the magnetoresistive effect element is formed is h, and the dimension in the X-axis direction of the magnetoresistive effect element is w, the magnetic body has a ratio h / The magnetic sensor according to claim 1, wherein w is 1 or more. 5. The magnetic sensor according to claim 1, wherein the magnetoresistive effect element is disposed inside the magnetic body forming region in the Y-axis direction . 6. The magnetic material according to claim 1, wherein the magnetic material is provided on a surface on which the magnetoresistive effect element is formed or a stacked structure including one or more insulating films. The magnetic sensor according to item 1. The magnetic sensor according to claim 1, wherein the magnetic body is a soft magnetic body. A measuring instrument comprising the magnetic sensor according to claim 1.

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